<template>
  <div class="spec-preview">
    <img :src="url ? url : skuDefaultImg" />
    <div
      ref="eventRef"
      class="event"
      @mousemove="mousemove"
      @mouseout="mouseout"
    ></div>
    <div class="big" ref="bigRef">
      <img ref="bigImgRef" :src="url ? url : skuDefaultImg" />
    </div>
    <div class="mask" ref="maskRef"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props: ["skuDefaultImg"],
  data() {
    return {
      url: "",
    };
  },
  mounted() {
    // 更改默认图片
    this.$bus.$on("changeImg", (url) => {
      this.url = url;
    });
  },
  methods: {
    mousemove(e) {
      const big = this.$refs.bigRef;
      const mask = this.$refs.maskRef;
      const event = this.$refs.eventRef;
      const bigImg = this.$refs.bigImgRef;
      big.style.display = "block";
      mask.style.display = "block";
      // 获取小图片左、上对应值
      let left = e.offsetX - mask.offsetWidth / 2;
      let top = e.offsetY - mask.offsetHeight / 2;
      // 防止越界
      if (left < 0) left = 0;
      if (top < 0) top = 0;
      if (left > event.offsetWidth - mask.offsetWidth)
        left = event.offsetWidth - mask.offsetWidth;
      if (top > event.offsetHeight - mask.offsetHeight)
        top = event.offsetHeight - mask.offsetHeight;
      // 改变位置
      mask.style.left = left + "px";
      mask.style.top = top + "px";

      // 移动大图片
      bigImg.style.left = -2 * left + "px";
      bigImg.style.top = -2 * top + "px";
    },
    mouseout() {
      this.$refs.bigRef.style.display = "none";
      this.$refs.maskRef.style.display = "none";
    },
  },
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  // .event:hover~.mask,
  // .event:hover~.big {
  //   display: block;
  // }
}
</style>